Analog modems are used for data communications between terminals or computers over dial-up and dedicated telephone lines. These modems typically have power applied continuously but are often used for only minutes a day. Considering the large installed base of modems, this adds up to large amounts of wasted power. In many cases power availability at a modem user site is severely limited. This causes complicated and often expensive methods to provide additional power for modem installation.
Efforts have been made to design low power modems. This has generally resulted in trade-offs in modem features and functionality as sacrifices were made in order to save power.